Prosthetic ligamentary device

Abstract

A prosthetic ligamentary device consists of one or two longitudinal elements of relatively inelastic material and an element of relatively elastic material. When the longitudinal elment (s) is or are subjected longitudinally to an anatomical tensile force, it or they extend (s) to a limited degree by transversely compressing the relatively elastic element, until the force is incapable of compressing the latter element further, whereupon the device becomes inextensible by the force. Two devices can be combined to form a cruciate ligament prosthesis for a knee joint.

We claim: 
     
       1. A prosthetic ligamentary device comprising a first means which is relatively inelastic longitudinally of the device, and a second means which is relatively elastic transversely of the device, said first means, at said second means and in one longitudinal direction of said first means, diverging outwardly and then converging inwardly, so that the subjection of the first means to an anatomical tensile force increases the length of the first means against the action of the second means to a limited degree and thereupon said first means becomes virtually inextensible by said force. 
     
     
       2. A device according to claim 1, wherein said first means diverges and converges as aforesaid about said second means and the latter is compressed by the extending of said first means, so that said first means is extensible until said second means can be substantially compressed no further by said tensile force. 
     
     
       3. A device according to claim 2, wherein said first means comprises a hollow longitudinal element of relatively inelastic material and said second means comprises a hollow element of relatively elastic material and contained in said hollow longitudinal element. 
     
     
       4. A device according to claim 3, wherein said hollow longitudinal element comprises a cross-woven cord. 
     
     
       5. A device according to claim 3, wherein said hollow element is a tube. 
     
     
       6. A device according to claim 2, wherein said second means comprises beads. 
     
     
       7. A device according to claim 1, wherein said second means comprises a compact body and said first means comprises first and second longitudinal elements which extend in said body in a manner in which they zig-zag towards and away from each other. 
     
     
       8. A device according to claim 1, wherein said second means is substantially encircled by an open-mesh sleeve disposed exteriorly of said first means and said second means. 
     
     
       9. A device according to claim 8, wherein said open-mesh sleeve is fastened at its ends to said first means at respective locations beyond said second means. 
     
     
       10. A device according to claim 1, wherein said first means terminates just beyond one end of said second means and at that termination zone has means facilitating sewing-in of a suture. 
     
     
       11. A cruciate ligament prosthesis, comprising first and second prosthetic ligamentary devices a section of at least one of which comprises relatively inelastic material displaceable between a longitudinally extensible condition and a longitudinally inextensible condition and linked with relatively elastic material displaceable between a relatively unstressed condition and a relatively stressed condition, and thereby that section, when in an initial condition in which said relatively inelastic material is in said longitudinally extensible condition and said relatively elastic material is in said relatively unstressed condition and then subjected longitudinally to an anatomical tensile force, increases in length to a limited degree and thereupon becomes virtually inextensible by said force and, when in its virtually inextensible condition and then relieved of said force, restores itself promptly to said initial condition. 
     
     
       12. A prosthesis according to claim 11, wherein said first and second prosthetic ligamentary devices form only three arms radiating from a region at which the arms are interconnected, one of the three arms being virtually inextensible when subjected longitudinally to an anatomical tensile force, and at least one of the other arms comprising said section(s). 
     
     
       13. A prosthesis according to claim 12, wherein said first and second prosthetic ligamentary devices comprise respective first and second hollow longitudinal elements which are of said relatively inelastic material and which extend one within the other to form said one of the three arms. 
     
     
       14. A prosthesis according to claim 11, wherein said first and second prosthetic ligamentary devices form first, second and third arms radiating from a region at which the arms are interconnected, said first arm being virtually inextensible when subjected longitudinally to an anatomical tensile force and the other arms comprising said sections. 
     
     
       15. A prosthesis according to claim 14, wherein said first and second prosthetic ligamentary devices form said first, said second, said third, and fourth arms radiating from said region, said fourth arm being virtually inextensible when subjected longitudinally to an anatomical tensile force. 
     
     
       16. A prosthesis according to claim 11, wherein said section(s) is/are encircled by a single open-mesh sleeve. 
     
     
       17. A prosthesis according to claim 16, wherein said sleeve is fastened at the ends thereof to the devices at locations beyond said sections and is of material which is extensible with said sections. 
     
     
       18. A prosthesis according to claim 11, wherein said sections are encircled by respective open-mesh sleeves. 
     
     
       19. A prosthesis according to claim 18, wherein said sleeves are fastened at the ends thereof to the devices at locations beyond said sections and are of material which is extensible with said sections. 
     
     
       20. A method of inserting a prosthetic ligamentary device at a joint between first and second bones, comprising: providing a prosthetic ligamentary device a section of which comprises relatively inelastic material displaceable between a longitudinally extensible condition and a longitudinally inextensible condition and linked with relatively elastic material displaceable between a relatively unstressed condition and a relatively stressed condition, and thereby that section, when in an initial condition in which said relatively inelastic material is in said longitudinally extensible condition and said relatively elastic material is in said relatively unstressed condition and then subjected longitudinally to an anatomical tensile force, increases in length to a limited degree and thereupon becomes virtually inextensible by said force and, when in its virtually inextensible condition and then relieved of said force, restores itself promptly to said initial condition, and   anchoring respective end zones of said device to the respective bones, with said section located between said bones.